KENDRIYA VIDYALAYA 6, JAIPUR

HALF YEARLY EXAMINATION-2024-25

CLASS- XI

SUBJECT- CHEMISTRY
Set-c

Time Allowed: : 3 hours Maximum Marks: 70

General Instructions:

a. There are 33 questions in this question paper with internal choice.

b. SECTION A consists of 16 multiple-choice questions carrying 1 mark each.

c. SECTION B consists of 5 very short answer questions carrying 2 marks each.

d. SECTION C consists of 7 short answer questions carrying 3 marks each.

e. SECTION D consists of 2 case-based questions carrying 4 marks each.

f. SECTION E consists of 3 long answer questions carrying 5 marks each.

g. All questions are compulsory.

h. The use of log tables and calculators is not allowed.

SECTION-A
1 Which one will have maximum numbers of water 1
molecules? (A)18 molecules of water
(B)1.8 grams of water
(C) 18 grams of water
(D) 18 moles of water
2 ……………. is the mass percentage of carbon in 1
carbo dioxide?
3 The second ionisation enthalpies of Na, Mg, Al and Si are in the order: 1
…………….

4 Consider the following species: 1

N3-, O2-, F–, Na+, Mg2+, Al3+
What is common in them?
(a) Radius (b) No. of protons (c) No. of nucleons (d) No. of electrons
5 Azimuthal quantum number determines the …………………………………… 1

6 The electronic configuration of Co2+ 1

ion is …………….

7 Transition metals belongs to 1

(a) Group number 1 to 2

(b) Group number 13 to 18

(c) Group number 3 to 12

(d) Group number 1 to 8

8 Bond enthalpy and bond dissociation energy of ……………………………molecule 1

is same.

9 The volume of gas is reduced to 1/8 from its original volume. 1

The specific heat will be……………………………………………

10 Which one of them is the weakest? 1

 (a) Ionic bond

(b) Covalent bond

(c) Metallic Bond

(d) van der Waals force

11 A measured temperature on Fahrenheit scale is 200F. What will this reading 1

be on the Celsius Scale?

(a) 40 ℃

(b) 94 ℃

(c) 93.3 ℃

(d) 30 ℃

12 The correct bond order in the following species is —————. 1

+ – 2+
(a) O2 < O2 < O2
– + 2+
(b) O2 < O2 < O2

2+ +
(c) OO –< O
2 2
<2
2+ – +
(d) O2 < O2 < O2

For questions 13-

16
(a) Both A and R are the true and R is the correct explanation of A.
(b) Both A and R are true but R is not the correct explanation of A.
(c) A is true but R is false.
(d) Both A and R are false.
13 Assertion (A): One atomic mass unit is defined as one-twelfth of the 1
mass of one carbon-12 atom.
Reason (R): Carbon-12 isotope is the most abundant isotope of carbon and
has been chosen as standard.

14 Assertion (A) : Atoms with completely filled and half-filled subshells are stable. 1
 Reason (R) : Completely filled and un-filled subshells have the

symmetricaldistribution of electrons and have maximum exchange

energy.
15 Assertion : BF3 molecule has zero dipole moment. 1
Reason :B is electronegative and B–F bonds are
polar in nature.

16 Assertion (A) :Work is not a state function 1

Reason (R) :Work done during the process depends upon the path followed

SECTION-B
17 What is the molar concentration of sugar C12H22O11 if it’s 2gm are dissolved in 2
enough water to make final volume 2L
18 (i)Calculate the number of electrons which will together weigh 5 gram. 1+1
(ii) Calculate the mass and charge of one mole of electrons.
19 (i) A photon of wavelength 4 × 10-7 m strikes on metal surface ; the work function of the 1
metal being 2.13 eV. Calculate (i) the energy of the photon,
(ii) the kinetic energy of the emission 1

20 In a process, 700 J of heat is absorbed by a system and 390 J of work is done 2

by the system. What is the change in internal energy for the process?
OR
Calculate the number of kj of heat necessary to raise the
temperature of 60 g of aluminium from 35°C to 55°C. Molar
heat capacity of Al is
24 J mol-1 K-1.
21 Account for the following:
(i) Both bond length of SO2 are same . 1
(ii) HF has higher boiling point than HCl.
1
SECTION-C
22 (i) An atomic orbital has n = 3. What are the possible values of l and ml ? 1+1+1
(ii) List the quantum numbers ml and l of electron in 3rd orbital.
(iii) Which of the following orbitals are possible ?
1py, 2s, 2px ,3f,5g,4f,1f and 2dX2-Y2
23 (i)Why HCl is polar whereas the Cl2 molecule is non-polar? 1
(ii) Out of sigma and pi bonds, which one is the stronger and why? 1
(iii) Which type of forces holds the atoms together in an ionic compound? 1
24 (i) Define adiabatic system. 1
(ii) What are the values of work done, internal energy and heat for 1
isothermal free expansion of an ideal gas? 1
(iii) Explain state and path functions with an example of each.
25 Draw enrgy level diagram of O2. Also calculate bond order and explain 3
magnetic character in O2.

26 a.Draw resonating structures of - benzene, PO4-3 , NO3- 3

b. Polarity of NH3is more than NF3 . explain it
c. He2 is ruled out. Why?

27 An element X with atomic number 112 has been recently predicted. Its
electronic configuration is :
[Rn] 5f146d107s2
. Predict 1
i. its group 1
ii. block in which this element would be placed 1
iii. IUPAC name and symbol.

28 In a reaction 3

A +2 B → AB2

Identify the limiting reagent in the following reaction mixtures.

(i) 300 atoms of A + 200 molecules of B

(ii) 2 mol of A + 3 mol of B

(iii) 100 atoms of A + 100 molecules of B

(iv) 5 mol of A + 2.5 mol of B

(v)2.5 mol of A + 5 mol of B

(vi)3gm of A +5 gm of B

SECTION-D
29 Read the passage given below and answer the following questions:
Hybridisation helps us to understand the geometry of molecules. This is because hybridized orbitals
are directed in space in some preferred direction to have stable arrangement , which determine the
geometry. The presence of lone pairs in addition to bond pairs distort the geometry due to repulsion.

a) What is the hybridisation of sulphur in SF4 1

b) give example of molecule having trigonal planer geometry. 1

c) Give shape of the molecule having four bond pairs and one lone pair . 1

d) Distinguish coaxial and collateral overlapping with example. 1

30 Read the passage given below and answer the following

questions: In the periodic table electronegativity increases
from left to right in a
period and decreases from top to bottom in a group. The
non-metallic character of an element is directly related to the
electronegativity while the metallic character is inversely
related to it.
a.The element with maximum electronegativity 1
belongs to (a) Period-1, Group-18
(b) Period-2, Group-
17 (c) Period-3, Group-
17
1
(d) Period-2, Group-1.
b.Which of the following groups contains metals, non-metals as well as
metalloids? (a) Group-1
(b) Group-
17 (c)
Group-14
(d) Group-2.
 c.The least, metallic element of group- 1
13 is (a) Aluminium
(b) Boron
(c) Gallium
(d) Indium.
d.The electronegativity 1
decreases with (a) decrease in
nuclear charge (b) increase in
atomic mass
(c) decrease in atomic
size (d) increase in atomic
number.

SECTION-E
31 a.The bromine atom possesses 35 electrons that contain 6 electrons in 2p orbital, 6 electrons in 3p 1
orbital and 5 electrons in 4p orbital. Which of these electrons experiences the lowest effective
nuclear charge?
b. The arrangement of the orbitals is based upon the energy based on the (n+l ) value. The lower the
value of the (n+l ), the lower energy found. For orbitals with equal values of (n+l), the orbital with 1
the lower value of n will have the lower energy.

1. Based upon the above-given information, arrange the following orbitals in the increasing order of
their energy
(a) 1s, 2s, 3s, 2p
1
(b) 4s, 3s, 3p, 4d

(c) 5p, 4d, 5d, 4f, 6s

(d) 5f, 6d, 7s, 7p

c. Wavelengths of the following different radiations have given below :

λ(A) = 300 nm
1
λ(B) = 300 μm

λ(c) = 3 nm

λ (D) 30 A°

Arrange the following radiations in the increasing order of their energies.

d. The Balmer series in the hydrogen spectrum corresponds to the transition from n1 = 2 to n2 =
3,4,………. This series lies in the visible region. Calculate the wave number of lines associated by the
transition in the Balmer series if the electron moves to n = 4 orbit. (RH= 109677 cm-1) 1
32 1. The net enthalpy change for the reaction is the amount of energy needed to break all the bonds 2
from the reactant molecules minus the amount of energy needed to form all the bonds in the
product molecules. What will be the enthalpy change for the given reaction?
2
H2(g) + Br2(g) → 2HBr(g)

Given that the Bond energy of the H2, Br2 and HBr is 435 kJ mol-1, 192 kJ mol-1, as well as 368
kJ mol-1, respectively.

2. Expansion of the gas in the vacuum is called free expansion. Calculate the work done as well as
the change in the internal energy if 1 litre of the ideal gas expands isothermally into a vacuum
until the total volume is 5 litres?
3. Entropy on boiling of egg ………………whereas curding of milk…………….
1

33 (i) Structures of molecules of two compounds are given below :

(a) Which of the two compounds will have intermolecular hydrogen bonding and which compound is 2
expected to show intramolecular hydrogen bonding.
1
(b) Which of the above two compounds will show lower melting point. Why?
(c) Solubility of compounds in water depends on power to form hydrogen
2
bonds with water. Which of the above compounds will form hydrogen bond
with water easily and be
more soluble in it